1. Field of the Invention
The present invention relates to a hybrid compressor having two compression mechanisms capable of being driven independently by drive sources separate from each other.
2. Description of Related Art
A hybrid compressor capable of being driven by an internal combustion engine of a vehicle or an electric motor, or both, is described in Japanese Utility Model (Laid-Open) No. 6-87678. Such a hybrid compressor includes two compression mechanisms: a first compression mechanism driven by an engine or an electric motor for driving a vehicle and a second compression mechanism driven by an electric motor exclusively used for driving the second compression mechanism (for example, an electric motor incorporated into the compressor).
Further, a hybrid compressor used in a refrigeration cycle for an air conditioning system for vehicles, which has a first scroll-type compression mechanism driven exclusively by the drive source for driving a vehicle and a second scroll-type compression mechanism driven exclusively by an incorporated electric motor and in which the fixed scrolls of the first and second compression mechanisms are disposed back-to-back, e.g., extend in opposite directions from a common or shared valve plate, and assembled integrally with each other, is described in Japanese Patent Publication No. JP-A-2003-232281. In such a hybrid compressor, each compression mechanism may be driven independently and both compression mechanisms may be driven simultaneously, and an optimum discharge performance of the compressor may be obtained depending on the requirements at the present time.
In the known hybrid compressors described above, the first compression mechanism driven by a drive source for driving a vehicle and the second compression mechanism driven by an incorporated electric motor usually are disposed coaxially. Therefore, for example, in a situation in which the compressor is mounted on a vehicle, so that the first and the second compression mechanisms are a substantially equal distance from a front end of the vehicle. When an impact force is applied to the front end of the vehicle in an accident or the like, the same-degree of force may be applied to each of the first and second compression mechanisms, and both compression mechanisms may be damaged similarly.
However, because a high voltage usually is applied to the incorporated electric motor, if the second compression mechanism portion of the compressor, particularly, the electric motor portion, is damaged, not only mechanical damage, but also current leakage may occur.